Fury sparred Joshua while the WBA, WBO & IBF Champion was still an amateur and claimed that although the Watford-born star "had a good couple of rounds" he then started to school the future Olympic gold medallist.
"We've had a spar before - amateur boxer he was at the time - he had a good couple of rounds then I started hitting him round the body," Fury said on Showtime.
"He was like this, lifting his legs up in the corner, there were 10 people in the gym who saw it.
"I'm there with my hands down, he’s coming forward with big swings, how’s he going to hit me? I said go on then, put one on me, I'll stand still."
Fury also recalled a recent confrontation between himself and Joshua when the 'Gypsy King', despite still being significantly out of shape, offered British boxing's megastar outside for a bare-knuckle bout.
Anthony Joshua hopes to face the winner of Fury vs Wilder in April (Getty)
“He seems pretty spirited, doesn’t he?
“But when I stood face-to-face to him and said, ‘Do you want to get outside?’ His a*** started flapping.
“He **** himself.
“It doesn’t matter what weight I was at the time, I wasn’t in shape, but I’d have took him outside and kicked his **** right in for him."
Fury is currently in training camp in California at Big Bear Lake having lost over 160lbs after his near three-year absence from the sport.
Yet, despite having only two comeback fights against significantly lower-level opposition - Sefer Sefari and Francesco Pianeta - Fury decided to jump straight into a fight with Wilder for the WBC Championship when negotiations between the undefeated Alabaman and Anthony Joshua broke down.